Starbridge by Jack Williamson and James E. Gunn is the story of one man against a Galactic Empire. Horn is a mercenary who agrees to kill one of the Masters of Eron, the powerful overlords who rule the galaxy through total control of the only means to cross interstellar space. Eron demands such a high toll for the privelege of using their system that whole planets have been reduced to the meanest of circumstances, while the Golden Folk of Eron live lives of absolute luxury, waited on hand and foot by the less fortunate.

When Horn sets out to perform this task, he discovers that it is not so easy. He meets up with Wu, an ancient Chinese man whose ragged parrot can actually talk, not just mimic words. The parrot turns out to be the last survivor of an incredibly ancient and wise race of living diamonds who were genocided by a ship of greedy pirates thinking to make a fortune. The "parrot," Lil, keeps Wu alive and creates the interstellar travel system.

Horn starts a revolution among the slaves on Eron, but is captured and exiled to the horrible prison planet of Vantee where nothing grows (although it neatly overlooks how free oxygen could be present without green plants to produce it.) He meets up with the pirate Redblade and leads the prisoners to do the impossible -- to escape.

They return to Eron, where they finally overthrow the rule of Eron and create a new free system. At the end it is revealed that Wu and Lil engineered the whole thing because the decadent Empire would not be able to stand against the approaching menace from Beyond, and that only vigorous free people would hold any hope for Humanity.

Unfortunately this book has gone out of print. It is possible to have Amazon.com search for a used copy, albeit at a premium.